Method and apparatus for heat treating a material and monitoring the material content x-ray spectrographically

ABSTRACT

An apparatus and method for the heat treatment of a material in an enclosure comprising an electron gun for treating the material and means for the spectrographic analysis of the X-rays emitted by the material under bombardment by the electron gun. The method is carried out by continuous spectrographic analysis of the Xrays produced so that a monitoring of the heat treatment is performed.

Z l 9 l 2 l 0 SR Oir=l5-7l XR 395859385 O Umted States Patent 1 1 3,585,385

- [72] Inventors Bernard Daigne [51] Int. Cl ..H0lj 37/00, Malakoff; G01n 23/00 Francois Girard, Paris, both of, France [50] Field of Search 148/128, [21] Appl. No. 726,059 129; 219/121 EB; 250/495 (0), 49.5 (7), 49.5 (8) [22] Filed May 2, 1968 145 1 Patented June 15, 1911 1 1 References clted [73] Assignee Office National DEtudes Et De Recherches UNITED STATES PATENTS Aerospafiohs 3,103,584 9/1963 Shapiro et a1 250/495 Chafillon-sws-Bagneux, France 3,196,246 7/1965 El-Kareh 250/495 x 1 Pflomy May 5, 1967 3,204,095 8/1965 Watanabe 250/495 1 1 France 3,080,481 3/1963 Robinson 250/495 x 105,259

Pnmary EmmmerW1ll1am F. Lindqurst Attorney-Strauch, Nolan, Neale, Nies & Kurz [54] METHOD AND APPARATUS FOR HEAT ABSTRACT: An apparatus and method for the heat treatment TREAnNG A MATERIAL AND MONITORING THE of a material in an enclosure com risin an 1 t f MATERIAL CONTENT X-RAY P g e gun SPECTROGRAPHICALLY treating the material and means for the spectrographlc analysis of the X-rays emitted by the material under bombardment l4 Chums 17 Drawing Flgs' by the electron gun. The method is carried out by continuous [52] US. Cl 250/495, spectrographic analysis of the X-rays produced so that a monil48/l28, 219/121 toring ofthe heat treatment is performed.

ELECTRON 1gGL$R$L 42 GU N / S U P P LY CONTROL X- RAY DETECTOR 0 CRUCIBLE I PATENTEDJUNI 5197i 3585385 SHEET 2 BF 5 ELECTRON GUN DETECTORS INVENTORS:

BERNARD M. DAIGNE FRANCOIS GIRARD Attys.

PATENTEUJUMSIHYH 3,585,385

SHEET 3 [1F 5 FIGS /|NTEGRATOR ELECTRON 1 I $sE-asRs F X- RAY DETECTOR DISTANCE FEGB A DISTANCE Y 0s A CE T N x FIG.7

I Yo 0 x ind t TIME 10 DISTANCE FIG.9 DISTANCE Q r F t t TIME to 4 t Em:

INVENTORS:

BERNARD M. DAIGNE FRANCOIS GIRARD Attys.

PATENTEU mm 3585385 SHEEI 8 0F 5 ENERGY H612 X0 x DISTANCE DISTANCE G DISTANCE x y to t ENERGY F5G.15

T FEGJB yo y DISTANCE INVENTORS:

BERNARD M. DAIGNE FRANCOIS GIRARD Attys.

METHOD AND APPARATUS FOR IIEAT TREATING A MATERIAL AND MONITORING THE MATERIAL CONTENT X-RAY SPECTROGRAPHICALLY The invention relates to an apparatus and installation for controlling the heat treatment of a material in an enclosure. Materials can be given heat treatment by means of installations of various kinds, used in dependence on the nature of the material to be treated. These installations differ from one another in accordance with whether the enclosure receiving the material has an atmosphere or is in vacuo, and also in accordance with the heating means used for treatment, such as electrical induction, laser beams, electron beams, etc....

In installations of the kind specified, contrpl means are ap plied some of which use spectrography of the Xrays emitted by direct excitation or fluorescence.

It is an object of the invention to provide an apparatus which enables a material to be given a heat treatment in better conditions than hitherto, inter alia for the purpose of obtaining a material of predetermined composition as a result of constant control. Another aim of the invention is to supply an installation comprising an apparatus of the kind specified which is simple in construction and convenient to use.

Another object of the invention is to provide a method and an apparatus for the treatment of a material whose treatment surface is of a relatively large size in relation to the section of a bombarding electron beam.

The invention will be clearly understood from the following description of an exemplary embodiment thereof, with reference to the accompanying drawings, wherein:

FIG. 1 is a highly diagrammatic view of an installation according to the invention;

FIG. 2 is a view of one embodiment of an installation according to the invention;

FIG. 3 is a similar view to FIG. 2 for a modification;

FIG. 4 is a view of an installation according to the invention, showing another embodiment;

FIG. 5 is a view of an installation according to the invention, for still another embodiment;

FIG. 6 is a diagrammatic view of an installation according to the invention;

FIGS. 7 1 1 are graphs;

FIG. 12 is a diagrammatic view of the surface of a'material during treatment;

FIGS. 13l5 are graphs;

FIG. 16 is a view similar to FIG. 12; and

FIG. 17 is a block diagram of an installation-according to the invention.

FIG. 1 shows a first embodiment of an installation according to the invention, in which material 20 for treatment is placed inside an enclosure 21 kept under vacuum by suitable means. The material 20 is subjected to the action of an electron beam 22 delivered by an electron gun 23 attached to the enclosure wall. According to the invention, the electron beam 22 is used on the one hand to treat the material 20 and on the other to excite in the material an X-radiation, a beam 24 of which enters a spectrographic apparatus 25 which is also disposed on the enclosure and whose output 26 affords spectrographic information on the composition of the material 20.

FIG. 2 shows an embodiment of an installation of the kind specified comprising aspectrographic apparatus according to the invention. The spectrographic apparatus comprises a first spectrograph 27 so controlled as to supply at its output 28 an electric signal proportional to the intensity of a ray L characteristic of a constituent A of the composite material 20. The apparatus also comprises a second spectrograph 29 so controlled as to supply at its output 30 an electric signal proportional to the intensity of a ray L characteristic of a second constituent B of the material 20. The signals at the outputs 28 and 30 pass through amplifying and integrating devices 31, 32 which deliver at their outputs 33, 34 signals representing intensities I 1,, of the rays L L 8 respectively. These signals are applied to a device 35 which produces their quotienti.e., /1 This quotient is, for instance, introduced via output 36 into a recording device 37. Another output 38 can be provided which is connected to a signalling and display device 39.

The value of the quotient I is independent of the conditions of excitation of the material 20 by the electron beam 22, to the extent to which the feed voltage of the electron gun 23 remains substantially constant; this is done in conventional manner.

In an installation according to the invention, therefore, the flux of the electrons of the beam 22 can be varied, for instance, to perform treatment in accordance with a desired program, without the information provided at the outputs 38 and 36 ceasing to be accurate.

The installation also enables the value of the concentrations C and Cg of the constituents A and B of the material 20- e.g., an alloy undergoing treatmentto be known at any moment. To this end, a calibration is first of all carried out on an alloy containing the constituents A and B and subjected to treatment in the same installation. After cooling, the alloy is subjected to a chemical analysis whose results enable the calibration to be performed.

After this calibration, the installation supplies information concerning an alloy in course of treatment which applies to the alloy in the solid state and which can therefore be immediately used.

The invention also provides embodiments using more spectrographs than two, thus enabling the concentration of a corresponding number of constituents to be determined.

In an embodiment, the invention provides an installation which substitutes a simple X-ray pickup device for one of the spectrographs.

The quotient of the intensity of a characteristic ray, for instance the ray L by the intensity of the signal at the output of the pickup device, given information about the concentration C, of the constituent A. Similarly, the concentration C of a constituent B can be determined with a second spectrograph, and so on.

The invention also provides an installation in which the same X-ray pickup device can be associated with a number of spectrographic channels corresponding to different wavelengths. An installation of this kind is shown in FIG. 3. An X-ray pickup device 43 is disposed at the input of a channel 44 comprising an amplifier 45 delivering at its output a signal which is applied to the device 35; the latter can also receive via a commutator 47 a signal proportional to the intensity of the ray L,, or of the ray L in dependence on its position, the information relative to the concentration C or C being at the output 48 of the device 35.

In the embodiment shown in FIG. 4, the material 20 is contained in a crucible 40, over which is disposed a device 41 for the metered supply of a constituent, for instance the constituent A. The device 41 is controlled by a device 42 itself controlled from the spectrographic signal at the output 26 of the spectrographic apparatus 25. The feed of one constituent can therefore at any moment be controlled by the actual composition at that moment of the material undergoing treatment, so that treatment can be performed in accordance with any required law.

FIG. 5 shows an installation with a servocontrol system, in which the spectrographic apparatus comprises two spectrographic chains, in a way similar to what was stated hereinbefore, with reference to FIG. 2.

The invention also contemplates a modification in which the beam of directed energy, for the treatment of the material, is not an electron beam but a laser beam.

The invention also provides a modification in which the material undergoing treatment is not heated by a directed beam of energy, but by electrical induction, for instance.

In the case of heating by a laser beam or by electrical induction, the invention provides an installation comprising an enclosure (not necessarily in vacuo), in which continuous monitoring and if necessary control is performed by analysis of the fluorescence phenomena produced by a mean of X-rays impinging on the material.

Reference is now made to FIG. 6. An electron gun 50 comprises devices for deflection in the directions 51 and 52, these devices being so disposed that the electron beam 53 can sweep the whole surface 54 of the material undergoing treatment, and also if necessary the surroundings of the surface, inter alia the output 62 of the device 55 supplying the added constituents. The assembly is contained in an evacuated enclosure 56. The installation also comprises an X-ray spectrometric device 57, whose output is connected to an integrator 58 which can have a number of output channels 59, 59'. The spectrometric device 57 is so mounted that it can aim at various points on surface 54. The installation enables the material to be treated by bombardment by the beam 53 and, at the same time, enables treatment to be controlled by the signals at i the output of the integrator 58 on the channel 59.

According to the invention, the surface 54 is periodically swept by the beam 53 in accordance with a law of displacement of the beam in relation to the time best meeting the requirements of the treatment conditions, a fraction of the sweeping period being spent in obtaining spectrographic information. To this end, the invention provides a preferred embodiment in which during said fraction of the sweeping period the electron beam is held immobile, its zone 60 of impingement on the surface 54 being in the sighting axis 61 of the spectrographic device.

A law of this kind is shown highly diagrammatically in the graphs (FIGS. 7, 8) which are merely illustrative. In FIG. 7, the time is plotted on the abscissa, the ordinate axis being a coordinate of a system of rectangular coordinates of the surface 54, for instance the x. The sweeping graph is, for instance, represented by the curve a, and the immobilization of the beam corresponding to the rectilinear portion a of the graph takes place for the abscissa x of the zone 60. FIG. 8 is a similar graph, but its ordinate axis refers to the other coordinate of the treatment plan--i.e., y-the time t being again plotted on the abscissa; the curve b corresponding to the treatment sweeping, and the portion b corresponding to the immobilization of the beam to obtain the spectrographic information. The fraction of the period t, devoted to obtaining the spectrographic information is smalle.g., between 1/10 and H100 of the periodbut it is adequate to enable the spectrographic analysis to have an accuracy which is independent of the treatment conditions. More particularly, any variations in energy which may occur have no adverse effect on the accuracy of the spectrographic analysis.

The invention also relates to the use of the spectrographic device itself for locating the zone of the treatment surface at which the spectrographic device is aimed. In one embodiment, during the fraction of the period devoted to analysis, there is first performed a y sweeping, by deflecting the beam in the direction 52, the abscissa x of the sweeping spot remaining constant. In that case the sweeping graphs are those shown in FIGS. 9 and 10. If no spectrographic signal is obtained during said fraction, a sweeping of the kind specified is restarted during the following period, but after the beam has been deflected by a small angle in the direction 51, the different abscissas where the sweeping is performed having been shown by the horizontal lines in FIG. 9. In this way the whole surface 54 can be scanned during successive periods. For a certain period, the spot passes on the zone 60 at which aims the spectrographic device 57, and the latter then delivers a signal over the channel 59'. By plotting the intensity of the signal on the ordinate axis, and the x values on the abscissa, there is obtained a graph such as that shown in FIG. 11, which enables the abscissa x, of the sighted zone 60 to be determined. FIG. 12 shows the band 63 swept during that fraction of the period during which the spectrographic signal was delivered, thus the one where is located the zone sighted by the spectrographic device. The double arrow f shows diagrammatically the direction of scanning, the perpendicular direction being that of sweeping. The value ofx, is noted, or stored. During the following periods, during the fraction of time r. of each period, the spot is held at a value of y, as shown by a horizontal line in FIG. 14, whereafter sweeping is performed at x, as shown in FIG. 13; if there is no signal on the channel 59, during the following period the x sweeping is restarted, but with a spot held at y at a different value than for the preceding period, until a signal appears on the channel 59', as shown in FIG. 15 for an ordinate y to which corresponds the maximum of the curve in FIG. 15 and which is that of the zone sighted spectrographically by the spectrometer 57.

In a modification, after determining the value of the abscissa x,,, as indicated hereinbefore, at each following fraction 1, the electron beam is held at x and a y sweeping is performed. If the sweeping amplitude is adequate-i.e., converse the whole treatment surface'the signal on the channel 59' will appear during the first fraction of the period, wherefrom there is derived the value ofy if the sweeping amplitude is smaller, it may be that no signal is produced during the first periods, and that the signal will be produced only when the swept zone passes over the spectrographically sighted zone. The hatched portion of FIG. 16 shows the zone swept during the fraction of the period during which the signal was produced in this case.

Whatever the embodiment, the value y is noted or stored. It is for the position of the beam 53 of the gun 50 for which its spot has the coordinates x and y that the beam is immobilized, during the following periods, for the fraction of time t corresponding to the spectrographic measurement.

A similar locating process is performed every time the orientation of the spectrographic device 57 is modified.

FIG. 17 is a block diagram of an installation according to the invention, comprising at least two spectrographic devices 70, sighted on the same point of the material under course of treatment, and each followed by an amplifier-integrator 71, 71' whose outputs are applied to a device 72 which forms their quotient. The quotient is applied to a transcoding device 73 with a measuring output 74. The movements of the electron beam of the gun 75 are controlled by an operational generator 76 for the treatment sweeping, an x-seeking device 77, a yseeking device 78, and an analytical device 79, x and y being fixed. The devices 77-79 are connected to a programmer 80 of time t The operational generator 76 is acted upon, via a flip-flop 81, both from the programmer 80 and the quotientforming device 72, with the interposition of an adapter 82 for the latter. The assembly of devices 7779 forms an operational generator 100 for the scanning and analysis sweeping. A programmer 83 of time t, is connected both to the operational generator 76 and to the operational generator 100. The flipflop 81 is followed by an x-storage device 84, a y-storage device 85, these two devices controlling an x and y-displaying device 86, and a write-out device 87 followed by an analysis programmer 88 which is connected to a switch 89 initiating the cycle for the automatic control thereof. Manual control 90 is also provided. The analysis programmer 88 is connected to the transcoding device 77 which comprises a second output for using the results 91, one output 92 of which is provided for controlling the means for supplying the constituents of the material undergoing treatment. The motors 93 for controlling the position of the-spectrometers are controlled from a control box 94 with the interposition of a programming device 95. An x-coding device 96 is connected to the x-seeking device and to the x-storage device 84, and a y-coding device 97 is connected to the y-seeking device and the y-storage device.

We claim:

1. A method of heat-treating material comprising at least two constituents by means of an electron beam bombardment and monitoring the heat treatment by X-ray spectrography, said method comprising the steps of:

a. biasing an electron beam source to produce an electron beam having an energy level sufficiently high to melt said constituents into a bath and to maintain saidbath in the liquid state while causing X-rays to be emitted therefrom;

b. collecting at least part of said X-rays emitted from said bath under the action of said beam,

c. spectrographically analyzing said X-rays to sample at least one monochromatic component of the X-rays emitted by one of said constituents,

d. measuring the intensity of said component, and generating a signal indicative of said measured intensity, and

e. modifying the content of said one constituent in response to said signal until a predetermined content of said one constituent in said material is obtained as indicated by a predetermined intensity of said component.

2. A method as claimed in claim 1, wherein there is measured a first component corresponding to one of said constituents and a second component corresponding to another of said constituents, the method further comprising the steps of:

a. generating a signal indicative of the ratio between the intensities of said first and second components to determine the relative concentration of said constituents, and

b. controlling the addition of one of said constituents into said liquid bath in response to said ratio signal.

3. A method for heat treating a material comprising at least two constituents and monitoring said heat treatment by X-ray spectrography, said method comprising the steps of:

a. biasing an electron beam source to produce an electron beam having an energy level sufficiently high to melt said constituents into a bath and to maintain said bath in the liquid state while causing X-rays to be emitted therefrom,

b. directing an X-ray spectrographic analysis device towards a zone of the bath to collect at least part of said X-rays emitted from said bath,

. sampling at least one monochromatic wavelength of said X-rays emitted by one of said constituents,

d. periodically scanning said bath including said zone with said electron beam, e. measuring the intensity of said monochromatic wavelength when said beam passes over said zone and generating a signal indicative of said measured intensity, and

. modifying the content of said one constituent in response to said signal until a predetermined content of said one constituent in said material is obtained as indicated by a predetermined intensity of said sampled monochromatic wavelength.

4. A method as defined in claim 3, further comprising the ranges of holding said electron beam stationary over said zone during a fraction of the scanning period time.

5. A method as defined in claim 4, wherein said time fraction ranges between H100 and 1/10 of the scanning period time.

6. A method as defined in claim 3, wherein said scanning step includes:

a. sweeping said beam along a plurality of coordinate paths parallel to the first of two rectangular coordinate axes while maintaining the beam at a substantially constant coordinate of the second axis,

b. determining when a signal ofa given value is generated by said spectrographic analysis and recording the coordinate along the first axis at which said signal is generated as a first coordinate of said zone,

c. sweeping said beam along a plurality of coordinate paths parallel to the second axis while maintaining the beam at a substantially constant coordinate of the first axis,

d. determining when a signal ofa given value is generated by said spectrographic analysis and recording the coordinate along the second axis at which said signal is generated as a second coordinate of said zone,

e. whereby the location of the zone is accurately located on said material.

7. Apparatus for heat-treating a material comprising at least two constituents and monitoring of said heat treatment by X- ray spectrography comprising, an enclosure housing said material, an electron gun, means for biasing said gun to produce an electron beam having an energy level sufficiently high to melt said constituents by forming a bath and to maintain said bath in a liquid state while causing X-rays to be emitted from said bath, detection means for collecting at least part of said X-rays emitted under the action of said beam, means for sampling at least one. monochromatic wavelength of the X-rays emitted by one of said constituents and for generating a signal indicative of the intensity of said wavelength, and means for controlling the addition of said one constituent in response to said signal, thereby providing a material having a predetermined content of said one constituent.

8. Apparatus as defined in claim 7, wherein said detection means comprise a first X-ray detector adjusted to detect a first wavelength characteristic of a first constituent, a second X-ray detector adjusted to detect a second wavelength characteristic of a second constituent, means for generating a signal representative of the ratio between the intensities of said first and second wavelengths, and means for controlling the addition of one of said constituents into said bath in response to said ratio signal.

9. Apparatus as defined in claim 7 for heat-treating a material including a plurality of constituents, wherein said detection means comprise a first detector sensitive to the continuous spectrum of the X-rays emitted, second and third detectors each adjusted to detect a wavelength characteristic of one of said constituents, means for generating a signal indicative of the ratio between the signals produced by said second and third detectors, respectively, and the signal produced by said first detector, switching means for selectively connecting said ratio signal-generating means to said second and third detectors, respectively, and means for controlling the addition of one of said constituents into said bath, in response to said ratio signal.

10. Apparatus as defined in claim 7, further comprising means for imparting a periodically scanning movement to the electron beam, and programmer means connected to said scanning means for controlling the scanning means in a predetermined manner.

11. Apparatus as defined in claim 7 further comprising means for holding the electron beam stationary on a zone of said material during a fraction of the scanning period ranging from l/10 to H of said period.

12. Apparatus for heat-treating a material comprising at least two constituents for the purpose of bringing the content of one of said constituents in said material to a predetermined value and monitoring the heat treatment by X-ray spectrography comprising, an enclosure housing said material, an electron gun, means for biasing said gun to generate an electron beam of an energy level sufficiently high to melt said constituents into a bath and to maintain said bath in the liquid state while causing X-rays to be emitted from said bath, means for deflecting said beam in a scanning pattern over said bath, a spectrographic analysis device for collecting said X-rays and sample therefrom at least one monochromatic component emitted by said one constituent, means for measuring the intensity of said component and generating a control signal indicative thereof, motor means for directing said spectrographic device towards a zone of said material, said beam deflection means including means for sweeping said beam along a plurality of coordinate paths parallel to one of two rectangular coordinate axes while maintaining the beam at a substantially constant coordinate of the second axis, said spectrographic device producing a signal when said beam passes over said zone thereby establishing the positional coordinates of said zone, means for holding said beam stationary for a short period of time at said coordinate position of said zone during each subsequent scanning period, and means for modifying the content of said one constituent in response to said control signal to obtain the predetermined value of said constituent as indicated by a predetermined intensity of said component.

13. Apparatus as claimed in claim 12, wherein said device comprises two X-rays spectrometers adjusted, respectively, to detect two different characteristic components of the X-radiation each corresponding to a constituent of the material, means for producing a signal indicative of the ratio between the intensities of said characteristic components, and means fist display means for indicating the coordinate position of said and for controlling the addition of one of said constituents into zone, and second display means for indicating the results of said material in response to said ratio signal. said spectrographic analysis.

14. An apparatus as claimed in claim 12, further comprising UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 585 385 Dated June 15, 1.971.

Inventor(s) Bernard gn Francois Girard It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 5, change "I to -I /I A/IB A B line 35, change "given" to --gives--.

Column 5, line 43, delete "ranges" and insert --step--.

Column 8, line 1, change "fist" to first--.

The printed row line of line numerals does not align with the printed lines of specification and claims.

Signed and sealed this 21st day of December 1971.

(SEAL) Attest:

ROBERT GOTTSCHALK EDWARD M.FLETCHER,JR.

Acting Commissioner of Patents Attesting Officer USCOMM'DC GOSTG-PBQ FORM 90-1050 (10-69) u s eovsnnuzm Pwmrme ornce; I969 o1ss:u 

2. A method as claimed in claim 1, wherein there is measured a first component corresponding to one of said constituents and a second component corresponding to another of said constituents, the method further comprising the steps of: a. generating a signal indicative of the ratio between the intensities of said first and second components to determine the relative concentration of said constituents, and b. controlling the addition of one of said constituents into said liquid bath in response to said ratio signal.
 3. A method for heat treating a material comprising at least two constituents and monitoring said heat treatment by X-ray spectrography, said method comprising the steps of: a. biasing an electron beam source to produce an electron beam having an energy level sufficiently high to melt said constituents into a bath and to maintain said bath in the liquid state while causing X-rays to be emitted therefrom, b. directing an X-ray spectrographic analysis device towards a zone of the bath to collect at least part of said X-rays emitted from said bath, c. sampling at least one monochromatic wavelength of said X-rays emitted by one of said constituents, d. periodically scanning said bath including said zone with said electron beam, e. measuring the intensity of said monochromatic wavelength when said beam passes over said zone and generating a signal indicative of said measured intensity, and f. modifying the content of said one constituent in response to said signal until a predetermined content of said one constituent in said material is obtained as indicated by a predetermined intensity of said sampled monochromatic wavelength.
 4. A method as defined in claim 3, further comprising the ranges of holding said electron beam stationary over said zone during a fraction of the scanning period time.
 5. A method as defined in claim 4, wherein said time fraction ranges between 1/100 and 1/10 of the scanning period time.
 6. A method as defined in claim 3, wherein said scanning step includes: a. sweeping said beam along a plurality of coordinate paths parallel to the first of two rectangular coordinate axes while maintaining the beam at a substantially constant coordinate of the second axis, b. determining when a signal of a given value is generated by said spectrographic analysis and recording the coordinate along the first axis at which said signal is generated as a first coordinate of said zone, c. sweeping said beam along a plurality of coordinate paths parallel to the second axis while maintaining the beam at a substantially constant coordinate of the first axis, d. determining when a signal of a given value is generated by said spectrographic analysis and recording the coordinate along the second axis at which said signal is generated as a second coordinate of said zone, e. whereby the location of the zone is accurately located on said material.
 7. Apparatus for heat-treating a material comprising at least two constituents and monitoring of said heat treatment by X-ray spectrography comprising, an enclosure housing said material, an electron gun, means for biasing said gun to produce an electron beam having an energy level sufficiently high to melt said constituents by forming a bath and to maintain said bath in a liquid state while causing X-rays to be emitted from said bath, detection means for collecting at least part of said X-rays emitted under the action of said beam, means for sampling at least one monochromatic wavelength of the X-rays emitted by one of said constituents and for generating a signal indicative of the intensity of said wavelength, and means for controlling the addition of said one constituent in response to said signal, thereby providing a material having a predetermined content of said one constituent.
 8. Apparatus as defined in claim 7, wherein said detection means comprise a first X-ray detector adjusted to detect a first wavelength characteristic of a first constituent, a second X-ray detector adjusted to detect a second wavelength characteristic of a second constituent, means for generating a signal representative of the ratio between the intensities of said first and second wavelengths, and means for controlling the addition of one of said constituents into said bath in response to said ratio signal.
 9. Apparatus as defined in claim 7 for heat-treating a material including a plurality of constituents, wherein said detection means comprise a first detector sensitive to the continuous spectrum of the X-rays emitted, second and third detectors each adjusted to detect a wavelength characteristic of one of said constituents, means for generating a signal indicative of the ratio between the signals produced by said second and third detectors, respectively, and the signal produced by said first detector, switching means for selectively connecting said ratio signal-generating means to said second and third detectors, respectively, and means for controlling the addition of one of said constituents into said bath, in response to said ratio signal.
 10. Apparatus as defined in claim 7, further comprising means for impartiNg a periodically scanning movement to the electron beam, and programmer means connected to said scanning means for controlling the scanning means in a predetermined manner.
 11. Apparatus as defined in claim 7 further comprising means for holding the electron beam stationary on a zone of said material during a fraction of the scanning period ranging from 1/10 to 1/100 of said period.
 12. Apparatus for heat-treating a material comprising at least two constituents for the purpose of bringing the content of one of said constituents in said material to a predetermined value and monitoring the heat treatment by X-ray spectrography comprising, an enclosure housing said material, an electron gun, means for biasing said gun to generate an electron beam of an energy level sufficiently high to melt said constituents into a bath and to maintain said bath in the liquid state while causing X-rays to be emitted from said bath, means for deflecting said beam in a scanning pattern over said bath, a spectrographic analysis device for collecting said X-rays and sample therefrom at least one monochromatic component emitted by said one constituent, means for measuring the intensity of said component and generating a control signal indicative thereof, motor means for directing said spectrographic device towards a zone of said material, said beam deflection means including means for sweeping said beam along a plurality of coordinate paths parallel to one of two rectangular coordinate axes while maintaining the beam at a substantially constant coordinate of the second axis, said spectrographic device producing a signal when said beam passes over said zone thereby establishing the positional coordinates of said zone, means for holding said beam stationary for a short period of time at said coordinate position of said zone during each subsequent scanning period, and means for modifying the content of said one constituent in response to said control signal to obtain the predetermined value of said constituent as indicated by a predetermined intensity of said component.
 13. Apparatus as claimed in claim 12, wherein said device comprises two X-rays spectrometers adjusted, respectively, to detect two different characteristic components of the X-radiation each corresponding to a constituent of the material, means for producing a signal indicative of the ratio between the intensities of said characteristic components, and means and for controlling the addition of one of said constituents into said material in response to said ratio signal.
 14. An apparatus as claimed in claim 12, further comprising fist display means for indicating the coordinate position of said zone, and second display means for indicating the results of said spectrographic analysis. 